Methods for obtaining aminoalcohols by the ring-opening addition reaction of epoxides with amines are generally performed at high temperature for a prolonged time using a large excess of amines. Since a large excess of amines are used, the conventional methods give rise to a lot of by-products and require the step of recovering amines; hence, if the amines are expensive, the conventional methods are not desirable not only from the viewpoint of production cost but also as an industrial production process. In order to realize an enhanced reactivity, it has been proposed that the above-described reaction be performed using Lewis acids but the Lewis acids that can be used are either expensive or labile and are not suitable for industrial use; perchlorates or the like are highly toxic and dangerous and because of this low level of safety, they have posed various problems such as the need to take utmost care in use (Non-Patent Documents 1 and 2). It was also reported that by using lithium bromide, the reactivity at room temperature under a solventless condition could be enhanced (Non-Patent Document 3). The method reported in that document uses amines and epoxides that are liquid at ordinary temperature, so its success is probably due to the reaction of the starting materials at high concentrations under a solventless condition. It then follows that this method is not applicable to amines and epoxides that are solid at ordinary temperature, especially those with high melting points.
Returning now to the compound of formula 1, it is produced by the ring-opening addition reaction of an epoxide with an amine as described in Patent Document 1. In this production method, (2R,3S)-2-(2,4-difluorophenyl)-3-methyl-2-[(1H-1,2,4-triazol-1-yl)methyl]oxirane (hereunder sometimes abbreviated as “epoxytriazole”) is used as the epoxide and 4-methylenepiperidine (hereunder sometimes abbreviated as “4-MP”) is used as the amine. In this method, the ring-opening addition reaction uses a large excess of 4-MP in water and involves prolonged heating under reflux, so it has the disadvantage that a lot of by-products are generated during reaction and need be removed. As a further problem, 4-methylenepiperidine which is produced by the method described in Patent Document 2 is obtained as dissolved in water, so its purity is low enough to affect the reactivity and impurities are unavoidably generated by the heat applied to the step of isolation by distillation.